Nuclear Structure and Electromagnetic Transitions Investigation in Er Isotopes within Framework of Interacting Boson Model

Interacting Boson Model-2 (IBM-2) is used to determine the Hamiltonian for Er nuclei. Fit values of parameters are used to construct the Hamiltonian, energy levels and electromagnetic transitions (B(E2), B(M1)) multipole mixing ratios (δ(E2/M1)) for some even-even Er nuclei and monopole transition probability are estimated. New ideas are used for counting bosons number at N = 64 and results are compared with previous works.     

142-164Dy核的低能谱和电磁跃迁的相互作用玻色子模型

采用IBM模型研究了^142-164Dy核的低能正宇称态的能谱和电磁跃迁。应用U(5)→SU(3)的简化哈密顿量较好地描述了它们的能谱和电磁跃迁。研究结果表明，该核基本属于U(5)→SU(3)的过渡核Spectra and E2 transition rates for the even even 142-164Dy isotopes are studied in the framework of the interacting boson model. A schematic Hamiltonian capable of describing their spectra and transition is used. It is found that the even even 142-164Dy isotopes are in the transition from U(5)to SU(3) dynamical symmetry.     

Investigation of Even-Even Ru Isotopes in Interacting Boson Model-2

The interacting boson model of Arima, Iachello, and co-workers is applied to the even ruthenium isotopes, ^96 Ru -116Ru. Excitation energies, electromagnetic transition strengths, quadrupole and magnetic dipole moments, and △（E2/M1） mixing ratios have been described systematically. Mixed symmetry states are investigated. It is seen that the properties of low-lying levels in these isotopes, for which the comparison between experiment and theory is possible, can be satisfactorily characterized by the Interacting Boson Model-2.     

有限玻色子系统中的激发态量子相变

为了探讨原子核系统中存在激发态量子相变的可能性,在相互作用玻色子模型框架下对有限玻色子系统中的激发态量子相变现象进行唯象分析,特别是针对角动量和有限N效应如何影响U（5）-SU（3）和SU（3）-O（6）过渡区中的激发态量子相变行为进行了系统研究。结果表明,低角动量振动谱中的激发态量子相变特征在现实玻色子数情况下可以很好地保持,但随着角动量增加相变特征逐渐消失。In this work, a phenomenological analysis of the excited-state quantum phase transitions (ESQPTs) in the finite-N boson system has been carried out within the interacting boson model in order to reveal the possibility of finding ESQPTs in nuclear systems. Particularly, the angular momentum and finite-N effects on the ESQPTs in the U(5)-SU(3) and SU(3)-O(6) transitional regions have been systematically investigated. The results indicate that the main features of ESQPTs can be well preserved even at a realistic boson number for small angular momentum but will gradually disappear as the angular momentum increases.     

Detailed Description of Mixed Symmetry States in 94Mo Using Interacting Boson Model

We have investigated the low-lying collective states and electromagnetic transitions in 94Mo within the framework of the interacting boson model. The influence of model parameters on the energy levels and electromagnetic properties has been investigated. The analysis of the obtained results and the parameter values predict that the 23+state is the lowest mixed symmetry state with pure F = Fmax - 1 in this nucleus. The calculated results predicate that the 25+ (two-Q-phonon) mixed symmetry state is closed to the J = 2+ at 2.870 MeV in the experimental data, and the 2.965 MeV state is the lowest mixed symmetry with J = 3+.     

The Structure of the Neutron-Rich Nd Isotopes in the IBM

The spectra and E2 transition properties of ^146-156Nd isotopes are studied in the interacting boson model in the light of new experimental data. It is found that ^146-150Nd are in the transition from the vibrational limit to the rotational limit. From ¹⁵²Nd onward, the isotopes are nearly perfect rotors. Possible deformation saturation is discussed in the interacting boson model.     

140-162Gd核的低能谱和电磁跃迁的相互作用玻色子模型

采用相互作用玻色子模型研究了140-162Gd偶偶核的低能谱和电磁跃迁,应用一个U(5)→SU(3)的简化哈密顿量很好地描述它们的低能谱和电磁跃迁过渡.结果表明140-162Gd同位素核基本上属于U(5)→SU(3)的过渡核.     

A correspondence between IBA-1 and IBA-2 models and electromagnetic transitions in the decay of some erbium isotopes

The interacting boson approximation IBA-1 model space, in which neutron and proton degrees of freedom are not distinguished, can be considered as a subspace of the IBA-2 model space. Using the microscopic background of the IBA-2 model, a correspondence can be established between IBA-1 and IBA-2 model space. Since the space of the IBA-1 model can be regarded as a subspace of the IBA-2 model there is a unique way to ‘Project’ the operators of the IBA-2 model onto those of IBA-1. This projection can be carried out using theF-spin formalism. In the IBA-2 model, the lowest states are indeed fully symmetric, and using the calculations with the help of this projection, we explore the energy levels and the electric quadrupole transition probabilitiesB(E2; {ie393-01}) and γ-ray E2/M1 mixing ratios for selected transitions of^{162, 164, 166, 168, 170}Er. Owing to admixtures of non-fully-symmetric states in IBA-2, we renormalized the parameters (ε) and (κ). This is the first time we show that this projection can be applied to some heavier isotopes and the results obtained for^{162, 164, 166, 168, 170}Er isotopes are reasonably in good agreement with the previous experimental values.     

^140-262Gd核的低能谱和电磁跃迁的相互作用玻色子模型

采用相互作用玻色子模型研究了^140-262Gd偶偶核的低能谱和电磁跃迁，应用一个U（5）→SU（3）的简化哈密顿量很好地描述它们的低能谱和电磁跃迁过渡．结果表明^140-262Gd同位素核基本上属于U（5）→SU（3）的过渡核．     

62-76Zn核的低能谱和电磁跃迁的相互作用玻色子模型(英文)

采用相互作用玻色子模型研究了62—76Zn核的低能正宇称态的能谱和电磁跃迁.应用一个简单的哈密顿量能够较好地描述它们的能谱和电四极跃迁.研究表明,62—76Zn同位素核基本上属于U(5)到O(6)的过渡核.Spectra and E2 transition rates for the even even 62-76Zn isotopes are studied in the framework of the interacting boson model. A schematic Hamiltonian capable of describing their spectra and transition is used. It is found that the even even 62-76Zn isotopes are in the transition from U(5) to O(6) dynamical symmetry.     

Energy Staggering in Ground Bands of 232Th and 236,238U Nuclei Using the Interacting Vector Boson Model

The ΔI=2 and ΔI=4 staggering parameters of transition energies E_γ for normally deformed positive parity ground bands in ²³²Th and ^236,238U nuclei are studied in framework of the symplectic extension of the interacting vector boson model. The model parameters are obtained from the fitting procedure between the calculated excitation energies and the corresponding experimental ones. The staggering parameters represent the finite difference approximations to higher order derivatives dⁿE_γ/d Iⁿ of the γ -ray transition energies in a ΔI=2 and ΔI=4 bands, which yielding multipoint formulae. The first order derivative (two-point formula) provides us with information about the dynamical moment of inertia. The staggering oscillation for the fourth order derivative (five-point formula) is about 0.5 KeV and is even larger than that in superdeformed bands. The quite similarity in dynamical moments of inertia of the isotopes ^236,238U up to high spin states indicate that the phenomenon of identical bands is not restricted to superdeformed bands.     

sdg IBM对稀土偶偶核基态形变的计算

用sdg IBM的内禀态,解析计算了稀土区的^152—164Dy、^154—168)Er、^170—186W、^168—194Os等偶偶同位素的基态形变,与其它理论及实验结果进行系统比较,表明sdg IBM能对核的形变作出很好的描述.     

基于微观IBM对电子-核散射及核电磁性质的研究(I) BE理论方案

从价核子自由度出发构造出核跃迁电荷/电流密度算符,采用Dyson玻色子展开技术给出了获取核玻色子形式跃迁电荷/电流密度有效算符的一种微观方法(BE方法).利用微观相互作用玻色子模型(IBM)提供的波函数可在玻色子态空间中求出核跃迁电荷/电流密度,结合电子-核散射以及核电磁跃迁的形式理论,建立了可研究电子-核散射各种形状因子,微分散射截面以及核约化跃迁几率、电磁多极矩、核态g因子等物理量的理论方案.在一种微观sdIBM-2框架下,结合现有理论方案,初步计算了     

Effects of single particle on shape phase transitions and phase coexistence in odd-even nuclei

A classical analysis of shape phase transitions and phase coexistence in odd-even nuclei has been performed in the framework of the interacting boson-fermion model. The results indicate that the effects of a single particle may influence different types of transitions in different ways. Especially, it is revealed that phase coexistence can clearly emerge in the critical region and thus be taken as a indicator of the shape phase transitions in odd-even nuclei.     

显微拉曼研究外延生长的BaTiO_(3-x)薄膜的结构相变与结构动力学(英文)

我们用显微拉曼、卢瑟福背散射谱、X射线散射和非对称摇摆等实验手段研究了在1 0 - 2 到1 0 - 5帕氧气压下用激光分子束外延技术生长的BaTiO3-x薄膜的结构动力学特性。测量结果表明生长氧压越低,晶格常数c和c/a越大,晶格常数a稍微减小,晶胞体积变大。随着生长氧压的减小,薄膜中氧含量减小。在3 0×1 0 - 5帕氧气压下生长的薄膜中氧缺陷可达0 48,但是样品的四方相结构可以很好的维持。显微拉曼研究进一步确定了样品都是四方相结构。另外,在BaTiO2 52 薄膜的拉曼光谱中发现高频段有两个新峰,其可能是由于氧缺陷导致的二级拉曼散射引起的。随着生长氧压的减小,拉曼峰向低频移动,表明薄膜中的应力减小。同时,拉曼峰变宽,这可能是由于氧缺陷导致的结构畸变引起的。由于在薄膜中存在二维张应力,BaTiO3单晶样品中的结构相变特征在我们的样品中从78到5 5 0K的温度范围内不存在。     

Structure of Hamiltonian Matrix and the Shape of Eigenfunctions：Nuclear Octupole Deformation Model

The structure of a Hamiltonian matrix for a quantum chaotic system,the nuclear octupole deformation model,has been discussed in detail.The distribution of the eigenfunctions of this system expanded by the eigenstates of a quantum integrable system is studied with the help of generalized Brillouin-Wigner perturbation theory.The results show that a significant randomness in this distribution can be observed when its classical counterpart is under the strong chaotic condition.The averaged shape of the eigenfunctions fits with the Gaussian distribution only when the effects of the symmetry have been removed.     

Critical Analyses of Order Parameter and Phase Transitions at High Density in Gross-Neveu Model

By critical analyses of the order parameter of symmetry breaking, we have researched the phase transitionsat high density in D = 2 and D = 3 Gross-Neveu (GN) model and shown that the gap equation obeyed by the dynamicalfermion mass has the same effectivenesss as the effective potentials for such analyses of all the second order and somespecial first order phase transitions. In the meantime we also further ironed out a theoretical divergence and proventhat in D = 3 GN model a first order phase transition does occur in the case of zero temperature and finite chemicalpotential.     

Critical Analyses of Order Parameter and Phase Transitions at High Density in Gross－Neveu Model

By critical analyses of the order parameter of symmetry breaking, we have researched the phase transitions at high density in D = 2 and D = 3 Gross-Neveu (GN) model and shown that the gap equation obeyed by the dynamical fermion mass has the same effectivenesss as the effective potentials for such analyses of all the second order and some specJal first order phase transitions. In the meantime we also further ironed out a theoretical divergence and proven that in D = 3 GN model a first order phase transition does occur in the case of zero temperature and finite chemical potential.     

Effects of Correlation between Network Structure and Dynamics of Oscillators on Synchronization Transition in a Kuramoto Model on Scale-Free Networks

A recent study has found an explosive synchronization in a Kurammoto model on scale-free networks when the natural frequencies of oscillators are equal to their degrees. In this work, we introduce a quantity to characterize the correlation between the structural and the dynamical properties and investigate the impacts of the correlation on the synchronization transition in the Kuramoto model on scale-free networks. We find that the synchronization transition may be either a continuous one or a discontinuous one depending on the correlation and that strong correlation always postpones both the transitions from the incoherent state to a synchronous one and the transition from a synchronous state to the incoherent one. We find that the dependence of the synchronization transition on the correlation is also valid for other types of distributions of natural frequency.